Since polyolefin is excellent in process-ability, toughness, water resistance, organic solvent resistance and chemical resistance and is low in specific gravity and inexpensive, it has been widely utilized as various molded articles, films and sheets for a long time.
However, polyolefin is generally not so high in heat resistance and stiffness and is required to be further improved in these properties for new uses.
On the other hand, polyphenylene ether has excellent heat resistance and stiffness, but has difficulties in processability and solvent resistance and thus is limited in scope of utilization thereof. In order to improve the processability and impact strength, blend with a styrene resin is utilized, but is inferior in solvent resistance and is limited in scope of use. For example, it is not suitable in the fields which require resistance to oily solvent such as gasolin containers.
Various blend composition have been proposed for utilizing merits of polyolefin and polyphenylene ether and supplementing their defects and there is a composition for improvement of processability and tensile strength (Japanese Patent Kokoku No. 42-7069), but this composition does not necessarily satisfy relatively high level of mechanical strength required in industrial fields. Furthermore, in order to improve compatibility of polyolefin and polyphenylene ether to increase mechanical strength, there were proposed compositions which contain a block copolymer of styrene and butadiene or hydrogenation product thereof (Japanese Patent Kokai Nos. 53-71158, 54-88950 and 59-100159) and compositions which additionally contain inorganic filler (Japanese Patent Kokai No. 58-103556). According to these proposals, processability and mechanical strength can be improved, but organic solvent resistance possessed by polyolefin is not sufficiently exhibited because addition amount of polyolefin is small or matrix (continuous phase) comprises polyphenylene ether or combination of polyphenylene ether with styrene resin. Furthermore, a composition which comprises polyphenylene ether to which is added polyolefin in a large amount of more than 20% by weight and is further added a diblock copolymer or radial teleblock copolymer comprising alkenyl aromatic compound having compatibilizing action and conjugated diene or hydrogenation product of these copolymers is disclosed in Japanese Patent Kokai Nos. 58-103557 and 60-76547. Moreover, there are disclosed a technique of grafting styrene compound on polyolefin and then adding thereto polyphenylene ether in Japanese Patent Kokoku No. 56-22544 and a technique of blending polyolefin copolymerized with glycidyl methacrylate or the like with polyphenylene ether in Japanese Patent Kokai Nos. 57-108153 and 58-225150. In addition, there are disclosed a technique of blending polyphenylene ether with both a polymer having glycidyl group and polyolefin having a group capable of reacting with glycidyl group in Japanese Patent Kokai No. 60-260449, a technique of blending polyphenylene ether with a modified copolymer obtained by polymerizing styrene compound with copolymer of glycidyl (meth)acrylate and olefin in Japanese Patent Kokai No. 61-47745, and a technique of blending modified polyphenylene ether and modified polyolefin with a binder having a specific structure in Japanese Patent Kokai No. 63-128056.
However, according to these conventional techniques, compatibility between polyphenylene ether and polyolefin is not necessarily satisfactory and as a result improvement of solvent resistance and mechanical strength is not sufficient and practically satisfactory materials have not yet been obtained.